Science

Posted by Marty Gingras on 2011-11-02 08:33:07
in reply to Re: Public Invited to Discuss Proposed Regulation Changes for Striped Bass posted by Marty Seldon on 2011-11-01 13:24:05

Hi all,

The link I posted to a directory of publications was my way of encouraging a discussion about the scientific merits of any approach to striped bass management. Since there is a lot of scientific material to wade through, I'll post some pertinent block quotes:

N. B. Scofield and H. C. Bryant (1926) "To the angler the striped bass is 'a gallant fish and a bold biter.' It is eagerly sought for by a host of anglers because of the excellent sport offered in its capture as well as the delectable white meat so desirable as food."

Eugene C. Scofield (1931) "Some questions regarding young chinook salmon as one of the foods of the bass have been repeatedly called to attention. During this investigation no salmon have ever been observed in the stomach of a bass. The lack of small salmon as a result of the serious depletion of this race is the probable reason none has been found in the stomachs of the voracious striped bass."

Leo Shapovalov and Alan C. Taft (1954) "Under certain conditions striped bass which have entered a stream may consume large quantities of seaward migrant trout and salmon, as shown by Shapovalov (1936). In that paper the writer described the stomach contents of 47 striped bass seined by A. C. Taft and himself in the upper end of Waddell Creek lagoon on April 26, 1935. The larger of these fish (37 to 49 cm. long) had been feeding largely on silver salmon and steelhead fingerlings and sculpins (Cottus), while the smaller bass (20 to 31 cm. long) had been feeding almost entirely on small crustaceans (Gammarus, Exosphaeroma, and Corophium), sticklebacks (Gasterosteus), and gobies (Eucyclogobius)."

Donald E. Stevens (1961) "The most important finding of this study is that young king salmon are a major food item in the diet of striped bass in the study area during June, July and Augustâ€¦The [delta smelt] was the most important food during March and April, and was also important during June and August."

John L. Thomas (1967) "At times striped bass feed heavily on their own young and on young king salmon. The effects of this predation on these populations can not be determined from the available data."

Peter B. Moyle (2002) "The major impact striped bass had on native species, especially salmon, presumably took place after their initial establishment as voracious predators capable of eating their way through large populations of juvenile salmon and other species. They may have had major responsibility for the extinction of thicktail chub and Sacramento perch, but we have no way of knowing for sure. Although Chinook salmon declined in the Central Valley as bass increased, there was also a virtually unregulated fishery for salmon at the same time, and hydraulic mining was devastating to many salmon spawning and rearing habitats. It is likely that striped bass continue to be an important predator on small salmon and that the decline of striped bass may have assisted recent increases in some salmon populations. On the other hand, large populations of other native fishes, such as delta smelt, longfin smelt, and splittail, thrived when bass were abundant, suggesting that they are capable of coexistence."

Matthew L. Nobriga and Frederick Feyrer (2007) "...striped bass likely remains the most significant predator of Chinook salmon, Oncorhyncus tschawytscha (Lindley and Mohr 2003), and threatened Delta smelt, Hypomesus transpacificus (Stevens 1966), due to its ubiquitous distribution in the Estuary and its tendency to aggregate around water diversion structures where these fishes are frequently entrained..."

Loboschefsky et al. (2011) "As expected, long-term trends in population consumption (total and prey fish) by all striped bass cohorts (ages 1 though 6) closely followed their respective population abundance trends. Population total consumption and prey fish-specific consumption by sub-adult striped bass was found to be similar to the population consumption by adult striped bass, due largely to the high abundance of sub-adults. Unlike adult striped bass that may emigrate and forage in the Pacific Ocean, the majority of sub-adult striped bass reside permanently within the [San Francisco Estuary]; hence, consumption by the relatively abundant sub-adult population may have significant impacts upon their estuarine prey species."